<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			var a4 = [1,2,3];
			var a5 = new Array(1,2,3);
			console.log(a4);
			console.log(a5);
			console.log(a4.concat(a5));
			
		</script>
	</body>
</html>
